Conventionally, there has been developed what they call a spiral freezer that is a food transfer heat treatment apparatus in which an endless transfer belt is spirally arranged in a storeroom, the food on the transfer belt is heat-treated, for instance, the food is cooled or frozen while being spirally conveyed together with the transfer belt in the storeroom.
The patent reference 1 (JP1995-81728) discloses an example of the food transfer heat treatment apparatus in which an endless transfer belt is spirally moved around a rotating drum that is vertically installed in a storeroom and is rotated around the center axis thereof, while the transfer belt is set in a spiral motion, by the rotation of the drum, along a spiral route around the outer periphery of the drum; and the food on the endless transfer belt is heat-treated for instance, the food is frozen. In addition, the an upper axis end of the rotating drum that is vertically arranged is suspended so as to be supported by the ceiling of the storeroom, as a cantilever is suspended from a ceiling and the top part of the cantilever is supported at a point on the ceiling. Thus, the rotating drum is suspended from the ceiling and the upper axis end part of the drum is rotatably connected to a drum driving means provided on the ceiling outside.
Thus, the disclosure of the patent reference 1 aims at ensuring a sufficient space between the lower end of the drum and the floor of the storeroom so that the floor cleaning can be easier, the heat generated by the drum driving means can be prevented from transferring into the storeroom, and the loss of the refrigerating power can be reduced.
Further, the patent reference 2 (JP2002-68436) discloses a food transfer and heat-treatment apparatus in which a heat-treatment-air generating device is arranged inside the space that is surrounded by the spiral transfer belt on which the food is placed and spirally conveyed. According to this disclosure, the space occupied by the apparatus can be remarkably reduced in comparison with the space occupied by a prior apparatus in which the space of the spirally conveyed belt and the space of the heat-treatment-air generating device are juxtaposed. Thus, the storeroom can be compact. Further, the heat-treatment-air streams vertically in the storeroom so that the travel distance of the heat-treatment air to the space of the spirally conveyed belt from the air blown-off place is reduced; as a result, the thermal efficiency is enhanced.
Further, the patent reference 3 (JP1998-157820) discloses a food transfer and heat-treatment apparatus in which the rotating drum of a cylindrical shape as is used in the patent reference 1 or 2 is not provided, and the food transfer and heat-treatment apparatus of the reference 3 is provided with a driving means for driving an endless spiral conveyer belt outside thereof.
According to this apparatus of the reference 3, inside the spiral conveyer belt can be arranged, a heat-treatment-air generating device that generates the air by which the food is frozen or heated. Thus, the footprint of the food transfer and heat-treatment apparatus can be reduced.
The patent reference 4 (JP1993-132115) and FIG. 1 thereof disclose a spiral conveyer (belt) in which;                an upward spiral conveyer route and an downward spiral conveyer route are provided so that both of the routes form an endless transfer belt (route);        the upward conveyer route is reversed into the downward conveyer route at a conveyer route of a S-shaped route (a S-shaped reverse route); and        the upward spiral route and the downward spiral route are repeated in turn along the vertical direction so that both routes form a laminated configuration in which the upward layer and the downward layer appear in turn.        
The patent reference 5 (JP2008-56489) is hereby explained on for reference although the reference 5 is disclosed after the priority date of the present invention; the reference 5 discloses a concrete configuration as to a belt of a chain conveyer. In consultation with FIGS. 15 and 16 of this application, the configuration of the chain conveyer belt is reviewed. As shown in FIG. 15, the conveyer belt 110 includes a series of adjacent links 111, and a lateral member 112 that is also referred to as a containment sidewall whereby the lateral member (a lateral plate) is placed at each left or right side of the plane (surface) of the belt, so that the lateral member is installed upright to the belt plane.
As shown in FIG. 16, each link 111 includes a U-shaped body part 121; thereby, at an end side of the U-shaped body part 121, an appendage part 122 is formed, the part 122 protruding toward the outside of the conveyer belt plane. Further, the U-shaped body part 121 comprises a pair of slots 123, and a pair of holes 124.
As shown in FIG. 15, the conveyer belt 110 comprises a plurality of conveyer rods 113 that forms the conveyer belt plane, the left end of each rod 113 is inserted into the holes 124 of a left side link 111 as well as into the slots 123 of an adjacent left side link 111; the right end of each rod 113 is inserted into the holes 124 of a right side link 111 as well as into the slots 123 of an adjacent right side link 111; and, both the ends of a conveyer rod 113 is locked to the holes 124 of a link; thus, each adjacent pair of links are connected to each other.
A tooth 114a of a cogged wheel 114 meshes with an appendage part 122 of a link 111. Thus, the drive power is transmitted to the conveyer belt 110 from the cogged wheel. Further, since the conveyer rod 113 can slide in the slots 123, the conveyer belt 110 can travel in a curved route while cornering left or right.
According to the disclosures of the references 1 and 2, there is, however, a difficulty in ensuring a sufficient space inside the spiral route of the conveyer belt, since the rotating drum that drives the conveyer belt is arranged inside the spiral route. Although the patent reference 2 discloses a configuration in which a heat-treatment-air generating device is arranged inside the limited space that the spiral route of the conveyer belt surrounds, the limited space is too small to freely arrange the heat-treatment-air generating device therein.
Further, in the technologies according to the references 1 and 2, the drive power as to the spiral conveyer (transfer) belt consists of the torque of the rotating drum, and the pulling power of the pulling device for the conveyer belt. An example of the pulling device for the conveyer belt may be a drive sprocket that makes the conveyer belt move by meshing mechanically with the conveyer belt. Since the pulling power is derived from a remarkable pulling force, the pulling power has to be great; therefore, the sum of the pulling power as to the conveyer belt and the drive power as to the heavy rotating drum becomes further greater. In other words, the drive energy saving as well as the space saving cannot be achieved so long as the rotating drum is used.
According to the technology disclosed by the patent reference 3, the drive mechanism for driving the spiral conveyer belt is separated without a rotating drum, so that the driving power can be saved. However, regarding the improvement means for improving the heat-treatment performance as to the heat-treatment-air, the disclosure by the reference 3 is limited within only an idea that the heat-treatment-gas can act on the subject products radially with an angle of radiation up to 360 degrees, from a point inside the spiral conveyer route. A further concrete configuration is not shown in the patent reference 3.
The patent reference 4 discloses a configuration as to the above-described spiral conveyer route. However, nothing is disclosed about a concrete means or configuration regarding the heat-treatment-air blowing against the transferred products conveyed by the spiral conveyer belt. Neither is disclosed any means or configuration regarding the construction simplification as well as the layout flexibility (allowable space) in constructing the spiral freezer.
The patent references quoted above are as follows:                Patent Reference 1 JP1995-81728;        Patent Reference 2 JP2002-68436;        Patent Reference 3 JP1998-157820;        Patent Reference 4 JP1993-132115;        Patent Reference 5 JP2008-56489.        